SOLUTION: So this has really confused me. Can someone help me solve it and offer an explanation? I would be forever grateful! Use the table below to find the indicated function values. x f

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Question 897423: So this has really confused me. Can someone help me solve it and offer an explanation? I would be forever grateful!
Use the table below to find the indicated function values.
x f(x)
-4 -3
-2 2
0 7
2 12
4 17
a. f(-4)
b. f(2)
c. For what value of x is f(x)=7

Found 2 solutions by richwmiller, rothauserc:
Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website!
You have two columns.
x and f(x)
Think of f(x) as y
Think of f(-4) as find y when x=-4
So look in the x column for -4 and you will find -3 so y =-3 which means f(-4)=-3
-4 -3
f(2)
find f(x) when x=2 or find y when x=2
2 12
For what value of x is f(x)=7?
means find x when y=7
so look in the f(x) or y column for 7 and find x
0 7

Answer by rothauserc(4718) (Show Source):
You can put this solution on YOUR website!
standard form for linear equation is f(x) = ax +b
now the function value (0, 7) gives us the value of b, that is,
f(x) = 7 = a(0) +b and b = 7
so far we have
f(x) = ax +7
let's pick another value, say (-4, -3), then we have
f(x) = -3 = a(-4) +7
-10 = -4a and
a = 10/4 = 5/2 and our equation is
f(x) = (5x/2) + 7
a) f(-4) = (5*-4/2) + 7
f(-4) = -10 +7 = -3
b) f(2) = (5*2/2) +7
f(2) = 5 + 7 = 12
c) f(x) = 7 = (5*0/2) +7 = 7
x = 0